You probably just gave her a brilliant idea.

Your sister needs help.

Rather than freeze it and end up with a catsicle, tell her to let it go.

Maybe she should see a taxidermist

Maybe try the freezer? like why a bag of ice.. wtf

A Feature Taxidermist?

Tell your sister that if she doesn't want to bury the cat -- which is what we do with dead friends and family, we bury them -- then she has to sleep with the cat on her bed at night and cuddle with it on the couch and so on. If your sister is not a small child or developmentally delayed, she needs to learn to mourn properly.

Yea. Stuff the pussy and mount it.

Did you really have to?

Maybe to help out your sister, wait for her to fall asleep to dispose the cat. Obviously she's having a hard time recovering from it dieing. And to go the extra mile, if the cat meant alot to her, get a clay paw print of it for her to keep. Losing animals is tough because they accept anyone no matter what skin color or ethnicity you are and are always there through thick and thin.